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Pinpoint Test B: Code 212 IDM Low, CMP CKT Open Or Erratic

WARNING: This page is about a different car, the 1994 Mercury Sable, 1994 Mercury Cougar, 1994 Lincoln Continental, 1994 Ford Thunderbird, and 1994 Ford Taurus. However, it is still accessible from the selected car via links, so may be relevant.

STARTING

  1. Verify Erratic Starting If vehicle is hard to start (requires more than one attempt to start and/or cranking speed is erratic), go to next step. If vehicle is not hard to start, go to step 4).
  2. Check CID Signal At ICM Turn ignition off. Install diagnostic cable. Connect diagnostic cable to breakout box. Connect diagnostic cable negative and positive leads to battery. Crank engine using starter (10 revolutions) while measuring voltage between J51 (CID D) and J60 (BAT-). If DVOM switches from less than 2 volts DC to more than 8 volts DC, replace ICM. If DVOM does not switch from less than 2 volts to more than 8 volts, go to next step.
  3. Check CID Signal At CMP Sensor Turn ignition off. Install CMP sensor tee. Crank engine using starter (10 revolutions) while measuring voltage between J21 (CID S) and J60 (BAT-). If DVOM does not switch from low to high voltage, replace CMP sensor. If DVOM switches from low to high voltage, repair open in CID circuit.
  4. Check ICM IDM Signal Output Turn ignition off. Install diagnostic cable module tee (terminals No. 7-12) to ICM. Connect diagnostic cable to breakout box. Connect diagnostic cable negative and positive leads to battery. Use Set DVOM on 20-volt AC range. Start engine. Measure voltage between J4 (IDM I) and J60 (BAT-). If AC voltage is more than 1.0 volt, go to next step. If AC voltage is 1.0 volt or less, go to step 6).
  5. Check IDM Circuit Continuity Turn ignition off. Disconnect PCM. Connect second breakout box to PCM wiring harness connector. Measure resistance between J4 (IDM I) of first breakout box and test pin No. 4 (IDM I) of second breakout box. If resistance is less than 5 ohms, replace PCM. If resistance is more than 5 ohms, repair open IDM circuit between ICM and PCM.
  6. Check PCM For IDM Circuit Fault If AC voltage is 1.0 volt or less in step 4), leave ignition off and PCM disconnected. Crank engine using starter (10 revolutions) while measuring voltage between J4 (IDM I) and J60 (BAT-) at breakout box. If DVOM switches from low to high voltage, replace PCM. If DVOM does not switch from low to high voltage, go to next step.
  7. Check IDM For Short To Power Turn ignition off. Disconnect diagnostic cable connector from ICM (terminals No. 7-12). Leave diagnostic cable connected to wiring harness. Turn ignition on. Measure voltage between J4 (IDM I) and J60 (BAT-). If DC voltage is 5 volts or more, repair IDM circuit short to power between PCM and ICM. If DC voltage is less than 5 volts, go to next step.
  8. Check IDM For Short To Ground With ignition off, measure resistance between J4 (IDM I) and J60 (BAT-). If resistance is more than 10,000 ohms, replace ICM. If resistance is 10,000 ohms or less, repair IDM circuit short to ground between PCM and ICM.
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